Anheuser-Busch InBev, owner of Budwieser, announced Wednesday it wants to purchase its largest competitor, SABMiller.
The Wall Street Journal said there was no formal terms or bid yet.
CNN Money reported that the deal would be the largest brewery merger in history, and among the top 10 largest mergers of all time.
However, such a large merger may violate antitrust laws in many countries.
"Antitrust regulators in every country where the two companies are in the top three will question a merger," University of Michigan School of Business Professor Erik Gordon told the Star Tribune.
All three sources report that large mainstream brewers have been under pressure from the rising trend in craft beers and independent breweries.